959
Q:

A student multiplied a number by 3/5 instead of 5/3, What is the percentage error in the calculation ?

A) 54 % B) 64 %
C) 74 % D) 84 %

Answer:   B) 64 %



Explanation:

Let the number be x.

Then, ideally he should have multiplied by  x by 5/3. Hence Correct result was x * (5/3)= 5x/3. 

 

By mistake he multiplied x by 3/5 . Hence the result with error  = 3x/5 

Then, error = (5x/3 - 3x/5) = 16x/15 

Error %  = (error/True vaue) * 100 = [(16/15) * x/(5/3) * x] * 100 = 64 %

Q:

A runner is running at a speed of 40 kim/h. If he runs at a speed of 30 km/h, then what will the decrease in the percentage of his speed be?

 

A) 30% B) 25%
C) 20% D) 15%
 
Answer & Explanation Answer: B) 25%

Explanation:
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1 105
Q:

If each edge of a cube is increased by 10%, then the percentage increase in its surface area is:

 

A) 22% B) 19%
C) 20% D) 21%
 
Answer & Explanation Answer: D) 21%

Explanation:
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1 296
Q:

A can finish a piece of work in a certain number of days. B takes 45% more number of days to finish the same work independently. They worked together for 58 days and then the remaining work was done by B alone in 29 days. In how many days could A have completed the work, had he worked alone?

 

A) 110 days B) 118 days
C) 98 days D) 120 days
 
Answer & Explanation Answer: B) 118 days

Explanation:
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0 163
Q:

The marked price and cost price of a book are and , respectively. The discount in percentage is:

 

A) 8 % B) 12 %
C) 15 % D) 10 %
 
Answer & Explanation Answer: B) 12 %

Explanation:
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5 310
Q:

If 40% of a number is less than its 60% by 30, then the 20% of that number is:

 

A) 40 B) 50
C) 30 D) 60
 
Answer & Explanation Answer: C) 30

Explanation:
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1 472
Q:

If the single discount equivalent to successive discounts of 20% and x% is 24%, then the value of x is:

 

A) 6% B) 5%
C) 4% D) 8%
 
Answer & Explanation Answer: B) 5%

Explanation:
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0 596
Q:

A crate of fruits contains one spoiled fruit for every 25 fruits. 60% of the spoiled fruits were sold. If the seller had sold 48 spoiled fruits, then the number of fruits in the crate were:

 

A) 3000 B) 2000
C) 1200 D) 2400
 
Answer & Explanation Answer: B) 2000

Explanation:
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0 206
Q:

The cost price of 12 pens is equal to the selling price of 8 pens. The profit percentage is:

 

A) 50% B) 45%
C) 40% D) 55%
 
Answer & Explanation Answer: A) 50%

Explanation:
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2 381